1.21+ for removing oceans

Trying to learn more about datapacks.
So my goal is to just remove the ocean and/or beaches from generating. 
Ultimately i want to remove water from rivers and remove ocean biomes altogether. I do NOT want to remove water from cave generation. From what i understand those are separate things. I care very little if it may make biome merging weird, as i will be controlling what biomes spawn anyhow.